Below the subgrid: uncertainties in supernova input rates drive qualitative differences in simulations of galaxy evolution. (arXiv:2004.03608v2 [astro-ph.GA] UPDATED)

Below the subgrid: uncertainties in supernova input rates drive qualitative differences in simulations of galaxy evolution. (arXiv:2004.03608v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Keller_B/0/1/0/all/0/1">Benjamin W. Keller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kruijssen_J/0/1/0/all/0/1">J. M. Diederik Kruijssen</a>

Feedback from core collapse supernovae (SNe), the final stage of evolution of
the most massive stars, has long been a key element in simulations of galaxy
formation. In this paper, we examine how simplifying assumptions made in
approximating the SN rates along with underlying physical uncertainty in those
rates can lead to large variations in the overall evolution of simulated Milky
Way-like galaxies. We find that the clustering of star formation is strongly
impacted by the delay between star formation and SN feedback. In addition, the
choice to use a realistic delay time distribution or instantaneous injection
for SN can have a significant impact on the galaxy. These effects appear even
when identical sub-grid models are used for coupling SN energy and momentum,
and the total SN energy budget is kept constant. In addition, we show that the
uncertain minimum SN progenitor mass has a significant impact on the SN energy
budget and injection timescale, and can completely change the overall evolution
of the galaxy. These underlying uncertainties mean that despite advances in the
sub-grid modelling of SN feedback, there are still serious difficulties in
constraining the effects of SN feedback. This complicates the task of comparing
different simulations to each other, as well as comparing simulations to
observations. We conclude by providing practical limits on the parameters of
subgrid models for SN feedback, which bound the uncertainty arising from SN
progenitor physics for future predictions from galaxy simulations.

Feedback from core collapse supernovae (SNe), the final stage of evolution of
the most massive stars, has long been a key element in simulations of galaxy
formation. In this paper, we examine how simplifying assumptions made in
approximating the SN rates along with underlying physical uncertainty in those
rates can lead to large variations in the overall evolution of simulated Milky
Way-like galaxies. We find that the clustering of star formation is strongly
impacted by the delay between star formation and SN feedback. In addition, the
choice to use a realistic delay time distribution or instantaneous injection
for SN can have a significant impact on the galaxy. These effects appear even
when identical sub-grid models are used for coupling SN energy and momentum,
and the total SN energy budget is kept constant. In addition, we show that the
uncertain minimum SN progenitor mass has a significant impact on the SN energy
budget and injection timescale, and can completely change the overall evolution
of the galaxy. These underlying uncertainties mean that despite advances in the
sub-grid modelling of SN feedback, there are still serious difficulties in
constraining the effects of SN feedback. This complicates the task of comparing
different simulations to each other, as well as comparing simulations to
observations. We conclude by providing practical limits on the parameters of
subgrid models for SN feedback, which bound the uncertainty arising from SN
progenitor physics for future predictions from galaxy simulations.

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